R

R

Redundant Array of Independent Disks (RAID)

A method used to standardize and categorize fault-tolerant disk systems. RAID levels provide various mixes of performance, reliability, and cost. Some servers provide three of the RAID levels: Level 0 (striping), Level 1 (mirroring), and Level 5 (RAID-5).

See also fault tolerance.

registry

A database repository for information about a computer's configuration. The registry contains information that Windows continually references during operation, such as: profiles for each user; the programs installed on the computer and the types of documents that each can create; property settings for folders and program icons; what hardware exists on the system; and which ports are being used.

The registry is organized hierarchically as a tree, and it is made up of keys and their subkeys, hives, and entries.

remote access policy

A set of conditions and connection parameters that define the characteristics of the incoming connection and the set of constraints imposed on it. Remote access policy determines whether a specific connection attempt is authorized to be accepted.

remote access server

A Windows-based computer running the Routing and Remote Access service and configured to provide remote access.

Remote Authentication Dial-In User Service (RADIUS)

A security authentication protocol based on a client/server model and widely used by Internet service providers (ISPs). RADIUS is the most popular means of authenticating and authorizing dial-up, virtual private network (VPN), wireless, and authenticating switch clients today. A RADIUS client is included in the Routing and Remote Access service that ships with the Windows Server 2003 family. A RADIUS server and proxy, named Internet Authentication Service (IAS), is included in Windows Server 2003, Standard Edition; Windows Server 2003, Enterprise Edition; and Windows Server 2003, Datacenter Edition.

See also authentication.

See also authorization.

See also Internet Authentication Service (IAS).

See also tunnel.

See also virtual private network (VPN).

remote procedure call (RPC)

A message-passing facility that allows a distributed application to call services that are available on various computers on a network. Used during remote administration of computers.

replication

The process of copying updated data from a data store or file system on a source computer to a matching data store or file system on one or more destination computers to synchronize the data.

In Active Directory, replication synchronizes schema, configuration, application, and domain directory partitions between domain controllers.

In Distributed File System (DFS), replication synchronizes files and folders between DFS roots and root targets.

See also Active Directory.

See also Distributed File System (DFS).

See also File Replication service (FRS).

reservation

A specific IP address within a scope permanently reserved for leased use to a specific DHCP client. Client reservations are made in the DHCP database using DHCP Manager and based on a unique client device identifier for each reserved entry.

See also Dynamic Host Configuration Protocol (DHCP).

See also IP address.

See also lease.

See also scope.

reverse lookup

A DNS query for a pointer (PTR) resource record that resolves an IP address to its corresponding fully qualified domain name (FQDN).

See also Domain Name System (DNS).

See also fully qualified domain name (FQDN).

See also IP address.

round robin

A simple mechanism used by DNS servers to share and distribute loads for network resources. Round robin is used to rotate the order of resource records (RRs) returned in a response to a query when multiple RRs of the same type exist for a queried DNS domain name.

router

A device or computer that forwards packets between interfaces based on a network layer destination address. For example, an Internet Protocol (IP) router forwards IP packets based on the destination IP address in the IP header. Routers typically use a routing table, which contains a series of entries for destinations and the corresponding next-hop address and interface to use to forward a packet to its eventual destination.

See also local area network (LAN).

See also wide area network (WAN).

Routing Information Protocol (RIP)

An industry standard, distance vector routing protocol used in small- to medium-sized Internet Protocol (IP) and Internetwork Packet Exchange (IPX) internetworks.

See also Internet Protocol (IP).

See also Internetwork Packet Exchange (IPX).

routing protocol

Any of several protocols that enable the exchange of routing table information between routers. Typically, medium- to large-sized TCP/IP internetworks implement routing protocols to simplify the administration of routing tables.

See also router.

See also routing table.

routing table

A database of routes containing information on network destinations, next-hop addresses and interfaces, and metrics for reachable network segments on an internetwork.